First Implantation of a Hybrid Tissue-Engineered Heart Valve in a Sheep's Mitral Position
Ramin Zareian1, Daisuke Morisawa1, Roger S. Geertsema1, Earl Steward1, Mariwan Majid1, Arti Kapadia1, Clinton Wynne2, Jeffrey C. Milliken1, Arash Kheradvar1.
1University of California, Irvine, Irvine, CA, USA, 2GE Healthcare, San Diego, CA, USA.
OBJECTIVE: This study aimed to test the short-term performance of a hybrid tissue-engineered heart valve (H-TEHV) implanted in an ovine model. The H-TEHV's leaflets are comprised of a non-degradable mesh scaffold enclosed between the layers of live tissues grown from the patient (sheep here).
METHODS: A H-TEHV scaffold with leaflets made of thin thermoplastic polyurethane mesh sewn to a titanium frame was developed for a sheep's mitral position. The jugular vein of a male castrated ovine model was harvested, the cells were extracted, isolated, expanded and finally sorted into two groups: a mixture of smooth muscle cells/fibroblast and endothelial cells. Then the valve scaffold was sequentially coated by those two layers of cells mixed with collagen type I over each side of the valve and incubated within a special two-piece mold for 7 days so that the tissues firmly form around and integrate with the leaflets' scaffold (Figures A and B).
RESULTS: Via open heart surgery using heart-lung machine, the H-TEHV was implanted in the mitral position of the sheep whose jugular vein was initially harvested (Figure D). Post-procedure echocardiography showed competent valve without leakage (Figure E). The animal was recovered from anesthesia and transferred on his feet to vivarium without any sign of stroke or other surgery-related problems. The animal died from pulmonary edema eight hours after completion of the surgery. The autopay showed the intact H-TEHV without any tissue dehiscence (Figure F).
CONCLUSIONS: We have successfully implanted an H-TEHV in sheep and assessed its performance in short-term and showed that H-TEHV can be a viable heart valve replacement. The animal survived the surgery and expired after eight hours due to pulmonary edema, potentially unrelated to the prosthesis. We are currently improving our post-surgical procedures to remedy pulmonary edema.
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